1. Field of the Invention
The present invention relates to a communication system for a motor vehicle, and more particularly to improvements in a communication system including microphone and speaker units mounted in a protective headwear.
2. Description of Background Information
In communication systems for a motor vehicle such as a motorcycle, there is a type of headset including a microphone and speaker units mounted in a full face type protective headwear. However, in such an arrangement there are several drawbacks relating to the speech sending and receiving performance. Specifically, since the microphone is disposed in the proximity of the speaker in the protective headwear, it was difficult to prevent howling and acoustic feedback between the microphone and the speaker in this arrangement. In addition to this problem, the microphone of this arrangement was subjected to noise caused by the breathing of the operator or other noises.
As for the speaker units of this arrangement, a problem existed in that a complex construction process is necessary to mount the speaker units inside the protective headwear causing a considerable increase in the cost of the protective headwear. Furthermore, since the ears of the operator are covered by the speaker units and the body of the protective headwear, it was usually not easy for the operator to listen to a sound from outside such as a siren of an ambulance car. Moreover, in the prior art audio circuit for this kind of communication system, there was no provision of means for helping the operator to listen to the sound from the outside.